I would order separate blinds for each of the double windows....and at least for now, skip any valance or panels. You have a lovely spare colonial look going, don't mess with it.
You could eventually do a simple gauze swag later if you want to soften it a bit....but I like the spare look.
However, I can't help but think you need a lamp and a table in the sitting room....for comfort.

You're going to need 2 separate shades for the double window. If you use one shade for both, it'll have to stick out too far from the window because of the wooden frame that separates them.

Thanks for the quick feedback. Lindac, you mean a lamp and table next to the red chair? The rest of the room looks like this (sorry for the mess, just took the pic). Opposite the sofa is the TV armoire, and the red chair is usually not that far in the corner but gets dragged towards the sofa. Unfortunately, the room is fairly long and narrow.
{{!gwi}}

Lovely room! I agree with Lindac about keeping it spare.
Would you mind sharing your paint color if you get a chance? Such a pretty, creamy yellow.

If you're doing an outside mount, you can get one long shade, but they are harder to manipulate and the strings are more likely to break. If you use 2 shades make sure they butt at the center so you get as close as possible to complete coverage.

You can do just a valance to add softness and color to the space. The corner windows in the breakfast area would be treated as one window....they make corner brackets for just such a situation. And if you don't like swags, don't do them....you can do a cornice board, and upholstered valance, pleated valances, etc.

The color is BM Windham Cream, a very soft creamy yellow. It's pretty true to real-life color in the pics of the family room. So far, I've been very happy with it in this north-facing room.

While we're at it: I hate the fan, but DH is in love with it. The compromise would be to replace the light kit, but so far I haven't seen any kind of fan lighting that I'd prefer. What style would you recommend as the least ugly?

Here is a link that might be useful: light kits

Since you are going with outside mount I would maybe take the shades all the way up to the ceiling. You definitely want them at least several inches above the window, so that when they are pulled up the entire window is uncovered.

I have inside mount lined bamboo blinds and think they'd be too hard to raise if they covered both windows. YMMV I do have an outside mount blind above the back glass door and have to admit that it doesn't look quite as *finished* as the inside mount ones, because it covers the white trim when lowered. So having them without curtain panels and outside mount to me will look ok, but perhaps more complete with panels. JMHO

Agree to do two shades on the double window but mounted on a single valance instead of having the valences butt up to one another. It's a much cleaner look.

Your walls are the same color as mine. I love it in northfacing rooms, very easy to live with and work around. Outside mounted shades look fine as long as they pull up into a nice casing . I know that sounds funny but my daughter bought a beatiful set for her kitchen that pulls up into a nice casing so they look nice up or down. When she bought the ones for the living room they didnt pull up into the box and looked very unfinshed. She was just trying to match colors and texture with the fist set and it didn,t occur to eigher of us that they might have a different look up.I would mount them above the window trim and two for the big window.